1. Field of the Invention
The present invention relates to a speaker structure. More particularly, the present invention relates to a speaker structure designed through using ferroelectric amount of the vibrating film.
2. Description of Related Art
Generally, vision and audition are two most direct senses for human-beings, so for a long time, scientists try their best to develop various relevant systems capable of reproducing vision and audition. Recently, as the increasing of people's demands on the sensing quality, and under a precondition that 3C products (computer, communication, and consumer electronics) have been developed towards the trend of being short, small, light, and thin, a power-saving, light, thin speaker designed according to ergonomics demand will have a great number of demands and applications in the near further, no matter it is matched with a large-size flat panel speaker, or used as small earphone for walkman, and stereophonic mobile phone.
Driving manners for electrostatic speaker may be approximately divided into three types, namely, dynamic, piezoelectric, and electrostatic. Recently, the dynamic speaker has been most widely used, and its technology is most mature. However, due to the disadvantages of the original architecture, it is impossible to be flattened in volume. Therefore, facing the challenge of the trend that the 3C product becomes light and thin and the home theater becomes flattened, it is impossible for the dynamic speaker to satisfy the market trend.
The piezoelectric speaker uses the piezoelectric effect of the piezoelectric material, and utilizes the material deformation characteristics of the piezoelectric material caused by the electric field to push the vibration film to generate sounds. Although the structure of the speaker is flattened and miniaturized, it has disadvantages of significant distortion and unstable, and it is difficult to satisfy the standard of the audition enjoyment required by the current people.
The electrostatic speaker is mainly Hi-end earphone and loudspeaker on the current market. The operating principle for the conventional electrostatic speaker is that two fixed electrode plates with holes are used to clamp a conductive vibrating film to form a capacitor, and then a DC bias is applied to the vibrating film and an AC voltage is applied to two fixed electrodes, and electrostatic force generated by the positive and negative electric fields is used to drive the conductive vibrating film to vibrate and to radiate sounds. The bias of the conventional electrostatic speaker must reach up to hundreds or even thousands of volts, so it is required to externally connect to an amplifier with a high unit price and a large volume, which is the reason that it cannot be popularized.
As for the electrostatic speaker, for example, in U.S. Pat. No. 3,894,199, an electro-acoustic transducer structure is mainly provided, as shown in FIG. 1. It includes two fixed electrode structures 110 and 120 placed on two sides. The fixed electrode structures 110 and 120 have a plurality of pores for scattering the generated sounds. A vibrating film 130 is disposed between the fixed electrode structures 110 and 120. A fixing structure 140 is made of an insulation material, and used to fix the fixed electrode structures 110 and 120 and the vibrating film 130. The fixed electrode structures 110 and 120 are respectively connected to an AC source 160 through a transformer 150. When an AC signal is transmitted to the fixed electrode structures 110 and 120, a potential is alternatively changed to enable the vibrating film 130 to generate vibration due to difference potentials on two sides thereof, and thereby generating corresponding sound. However, the above configuration needs to enhance the sound-pressure output, so an additional power element is required to work together with the driving process. In this manner, not only the apparatus has a large volume, but also relatively more elements are used, and the cost is also relatively high. In addition, the fixing structure 140 must fix the fixed electrode structures 110 and 120 and the vibrating film 130, so the electro-acoustic transducer structure cannot achieve the flexible characteristics.